They put you on an heartbeat monitor and you hit the clicker everytime you feel the baby move. It puts marks on the read out page and then they count them to see how active baby is.

Then they do an ultrasound to measure the amount of amniotic fluid in your tummy. The further you go in pregnancy the less fluid and it becomes a danger for baby. I had 2 because I was over due! Was due 8/30/03 delivered on 9/06/03.

HTH & Hope I am right! lol

ETA: They only get worried about the amount of fluid when you are overdue!